Airplane-wing spar



July s 1924.

v. E. CLARK AIRPLANE WING SPAR Filed Feb.' 4, 1922 Invenlur. W

Patented July 8, 1924.

UNITED STATES PATENT OFFICE.

VIBGINIUS'E. CLARK, OF'DAYTON, OHIO, ASSIGNOR TO DAYTON-WRIGHT COMPANY, OF DAYTON, OHIO, A CORPORATION OF DELAWARE.

AmrLANE-WI'NG s'ran. Y

Application led February 4, 1922. Serial No. 534,227.

To all whom it may concern.'

Be it known that I, VIRGINIUB E. CLARK, a citizen of the United States of America, residing at Dayton, county of Montgomery, and State of Ohio, have invented certain new and useful Improvements in Airplane- Wing Spars (Docket of which the following is a full, clear, and exact description.

This invention relates to an all metal truss of very light construction especially` adapted for use as spars in internally braced air lane wings.

4n object of this invention is to provide a truss suitable for airplane spars which'is very strong for its weight, capable of easy adjustment of its diagonal brace members,

yand economical tomanufacture.

Further objects and vadvantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing, wherein a preferred form of embodiment of the present invention is clearly shown.

In the drawing:

Fig. 1 is a transverse section of a wing spar built according to this invention, a part being broken out to indicate that the vertical struts may be of varying lengths.

Fig. 2 is a side elevation of a part of the spar shown in Fig. 1.

Fig. 3 is a transverse section showing a modification of several features of the spar, one of which being the single diagonal brace wires.

Fig. 4 is a detail view. showing a method of attaching the diagonal wires to the sheet metal.

Fig. 5 is a section on line 5-5 of Fig. 3, showing the modified form of strut.

In the drawing similar reference characters refer to similar parts throughout the several views.

The spar shown in Figs. 1 and 2 is composed of the top and bottom beam members 10 built up out of sheet metal as clearly illustrated, the tubular strut members 11, 'and the double diagonal brace wires 12. The box section beam members 10 are made up of the two sections 13 and 14. The section 13 is provided with the reentrant fold 15 which serves as a recess for the dat ends of the struts 11. One of the sections 13 is also bumped-up, as shown in detail in Fig. 4, to provide a dat bearing area. for the flanged nuts 20 by which the tension on the brace wires 12 'is adjusted. Of course, if desired, the wires 12 may be fastened at both ends by means of the nuts 20, however, I prefer to provide the wires 12l at one end with a head set at an angle, as shown in Fig. 2, which obviates the necessity of bumping-up both of the sections 13.

The tubular struts 11 are flattened at their ends and a single rivet is passed through each strut end and the fold 15 of section 13. The struts 11 and the double brace wires 12 are all inserted before the sections 14 are riveted to the sections 13. Of course the tension on wires 12 may be adjusted at any time by applying a'wre'nch to the hexagonal nut' 20, after which the lock nut 21 is tightened.

In Fig. 3 I have shown a modification wherein there are only single diagonal brace wires 12 instead of the double wires 12 shown in Fig. 1.l Preferably the alternate brace wires 12 which run in the same direction, for example, the alternate lift wires 12', are placed on alternate sides of the spar in order minimize any tendency to bend the spar laterally. 1

` In Fig. 3 "I have also illustrated a modified form of box'section beam member wherein the edges of plates 13 and 14 are extended and curled over to increase the moment of inertia of the spar section. and hence its strength. Fig. 3 a so illustrates a modified form of strut 11 of the section shown in detail in Fig. 5. This strut is shaped from sheet metal, the ends being flattened out similar to the ends of the tubular struts 11. j

Spars constructed according to this invention are especially adapted for use in very spar over a beam spar are greater. This invention is also especially applicable to internally braced wings of varying depth since a tapered spar may be easily formed simply by varying the lengths of the strut members and brace wires and using the same section of beam members throughout the length of the spa-r. However, if desired, the size of the beam members may be also reduced as the bending moment decreases. This reduction in the beam members may be done either by tapering the box section of the beam, or by splicing together shorter lengths, the successive lengths being of lighter gauge thick wings where the advantages of a truss f ness of plates as the bendlng i moment decreases.

While the form of mechanism` herein shown and described constitutes a preferred form of embodiment of the present invention, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What I claim is as follows:

1. An airplane wing spar, comprising upper and lower beams built up from sheet metal, struts spaced at intervals. between said beams, and diagonal brace wires between said struts, said beams having salient folds and said wires being secured thereto at said salient folds.

2. A truss adapted for use as air lane wing spars, comprising upper and ower box section beams built up from' sheet metal, struts spaced at intervals between said beams, and dia onal brace members between said struts, sai struts being pinned directly to said beams.

3. A truss adapted for use as airplane wing spare, com rlsing upper and lower box sectlons beams uilt up from sheet metal,

'Struts spaced at intervals between said beams, and da. onal brace members between said struts, sald diagonal brace members extending into the box section beams and being supported on the interior thereof.

4. A truss ada ted for use as airplane wing spars, comprising upper and lower box section beams built up from sheetv metal,

nsoosu dia onal brace members between said struts,

sai brace members being provided with screw threaded flan -headed nuts at one end for securing said race member to one of said beams and for adjusting the length thereof.

6. A truss adapted for use as ai lane wing spars, comprising, upper and ower beams, struts spaced rat 'intervals between said beams, and diagonal brace members between said beams, said brace mem-- bers being secured to one' of said beams by extending through anv a erture therein and having an enlarged hea beyond said aperture. l

7. A truss adapted for use as ai lane wing spars, comprising, upper and ower beams, struts spaced at intervals, between said beams, and dia onal brace members between said beams, said brace members being secured to one of said beams by being screw threaded into a swivel means extending thorugh an'aperture in said beam.

In testimony whereof I hereto aix my signature.

V. CLARK.. Witnesses Gao. E. Pasco, Wn. P. Paseo. f 

